MEMS package and method for the production thereof

ABSTRACT

A micro electro-mechanical systems (MEMS) package is described herein. The package includes a carrier substrate having a top side, a MEMS chip mounted on the top side of the carrier substrate, and at least one chip component on or above the top side of the carrier substrate or embedded in the carrier substrate. The package also includes a thin metallic shielding layer covering the MEMS chip and the chip component and forming a seal with the top side of the carrier substrate.

CROSS REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 USC §120, this application claims the benefitPCT/DE2006/001945 filed Nov. 6, 2006 which claims the benefit of GermanPatent Application No. 102005053765.0 filed Nov. 10, 2005. Each of theseapplications is incorporated by reference in its entirety.

BACKGROUND

There is an enormous pressure to miniaturize the electronic componentsof mobile communications devices. This applies especially for MEMScomponents (micro electro-mechanical systems), such as, e.g.,microphones, which have a relatively high-profile design and thusrepresent limitations for the device design of mobile communicationsdevices.

From the published US Patent Application No. 2005/0185812A1, amicrophone housing is known in which a microphone constructed as a MEMScomponent is arranged together with a semiconductor chip on a baseplate, and in which the MEMS package comprises a common cap with whichthe MEMS component is covered against the base plate. The base plate canhave a sound entrance opening in its bottom side opposite the cap, sothat the entire component can be soldered onto the printed circuit boardreverse side, which faces away from the sound source. For this purpose,a corresponding hole must be provided in the printed circuit board. Inanother construction, the sound entrance opening can be provided in aconventional way on the top side in the cap, so that the component withthe base plate can be applied onto the surface of the printed circuitboard facing the sound source.

For mobile communications devices, additional problems result due to thesmall distance of the antenna from the electronic components, which aretherefore exposed to electromagnetic noise that can negatively influencethe functioning of the components.

SUMMARY

The task of the present invention is to specify a MEMS package ofsmaller structural size which constitutes a secure enclosure for a MEMScomponent, which better shields electromagnetic interference, and at thesame time is easy to produce.

The MEMS package according to the invention is built on a mechanicallystable carrier substrate. A MEMS chip is mounted on its top side.Likewise, at least one chip component is arranged on or above the topside of the carrier substrate or embedded in this substrate. A metallicshielding layer covers the MEMS chip and the chip component and forms aseal with the top side of the carrier substrate in an annular, closedperipheral region. The MEMS chip and chip component have electricalcontacts which are connected electrically to external contacts on asurface of the carrier substrate.

The shielding layer is a thin metallization layer which can be depositeddirectly onto the MEMS chip and/or the chip component. In addition,however, an enclosure can be provided at least between the MEMS chip andshielding layer. The shielding layer is preferably electricallyconnected at one or more positions to suitable electrically conductivestructures of the carrier substrate. Such structures can be groundpotential, additional shielding surfaces, or external connections.

A MEMS package is obtained which has only a minimal overall height. Theshielding layer guarantees electromagnetic shielding, which allows theuse of the MEMS package in an environment in which the irradiation ofelectromagnetic waves is to be taken into account. Such an environmentcan be, for example, the interior of a mobile radio terminal device.

The MEMS chip realizes an arbitrary sensor or actuator function and canbe realized in the form of a structured thin-film construction on a basechip used as a carrier. As an alternative or in addition to thethin-film construction, the MEMS chip itself can be structured and canoptionally even be monolithic for realizing the sensor or actuatorfunction. This side of the MEMS chip is designated below as the activeside. The MEMS chip has metallic contact surfaces by means of which itcan be connected electrically. The contact surfaces can be arranged onthe active side or on the opposite “passive” side of the base chip. Inthe latter case, the electrical connection of the contact surfaces toelectrically conductive structures of the active side can be performedby means of a connection running through the base chip. This can beconstructed as a via contact, that is, as a hole or borehole, which isfilled with an electrically conductive material, and in particular, withmetal. However, it is also possible to use as the base chip asemiconductor chip that is set to be electrically conductive in theregion of the via contact.

The external contacts of the MEMS package are located on one surface ofthe carrier substrate, preferably on the surface opposite the MEMS chip.The external contacts are connected in an electrically conductive way tothe terminal surfaces of the MEMS chip and/or to other circuit elements.Preferably, the MEMS chip is connected only indirectly to the externalcontacts by means of other circuit elements, such as, e.g., by means ofthe chip component.

The chip component is connected either directly to the carriersubstrate, or to terminal surfaces provided on this substrate and theseterminal surfaces are connected to the external contacts of the carriersubstrate. However, it is also possible to connect the chip component tothe MEMS chip electrically and to provide for both connected componentsa common connection to the terminal surfaces of the carrier substrate.

The carrier substrate can have electrical feedthroughs, which aresimilarly constructed as via contacts. The carrier substrate can have aone-layer or multi-layer construction. It can include ceramic or plasticmaterial and in the interior it can have one or more metallizationlayers, which are separated from each other by electrically insulatinglayers but which are connected to each other by means of the mentionedfeedthroughs. In this way, a circuitry structure can be realized in thecarrier substrate and connected to the MEMS chip and/or the chipcomponent. The circuitry structure can also include passive components,which are constructed from structured metallization layers and whichrealize capacitors, inductors, or resistors.

Preferably, the one or more chip components compose an integratedcircuit which interacts with the function of the MEMS chip. For example,the integrated circuit can be a control, evaluation, or amplificationcircuit or some other circuit arrangement used for operating the MEMSchip.

If the MEMS chip is not suitable for direct coating with a metallicshielding layer or if an embedded cavity, e.g., an acoustically activevolume, is to be realized specifically, then an enclosure is arrangedbetween the shielding layer and the MEMS chip. The enclosure can form aseal with the top side of the carrier substrate and can completelyenclose the MEMS chip between itself and the carrier substrate. Such alarge surface area enclosure can be realized, for example, in the formof a laminate film. This can be applied in such a way that it liesdirectly on the surfaces of the MEMS chip and carrier substrate orleaves intermediate spaces in some positions.

The laminate film is preferably a one-layer or multi-layer finished filmthat is converted into a hardened state during or after application,which can be effected, for example, by means of lamination. The laminatefilm, however, can also be generated by film casting directly on thesurface of the carrier substrate and MEMS chip. In this case, a laterhardening of the plastic material is also effected. However, it is alsopossible to generate the enclosure in a film form by means of a layergeneration process, for example, by casting or spraying or by means ofdip coating.

The enclosure, however, does not have to form a seal with the carriersubstrate and can lie on or be attached to the top side of the MEMSchip, for example, only in the form of a cover. In this case, the covercan also be a plastic layer or can be constructed from a thick plasticfilm. Preferably, however, the MEMS chip is covered with a mechanicallystable and especially rigid cover, which has a thermal expansioncoefficient adapted to the material of the MEMS chip or the base chip.From this standpoint, materials such as glass, quartz, or semiconductorlayers are suitable.

Such a cover can be adhered, bonded, soldered, or connected by means ofbumps.

For certain functions of the MEMS chip it is necessary to provide abovethe MEMS chip an adequately sized recess, which is used for forming aback-side or reference volume or for exposing structures lying deeper inthe MEMS chip. For this purpose it is possible to provide, in theenclosure formed as a cover, a recess that encloses together with theMEMS chip a cavity facing toward the MEMS chip.

In another construction, for enclosure of the MEMS chip the chipcomponent is used as the cover, which lies on and is connected to theMEMS chip. The connection can include an electrical and a mechanicalconnection, wherein a flip-chip arrangement is preferred which realizesboth connections in one step or with the same structure. Thisarrangement has the advantage that a simple electrical connectionbetween the chip component and MEMS chip can be produced, that the MEMSchip is protected by the chip component, and that the chip componentused as a cover allows the direct application of the shielding layer.Thus, overall an extremely space-saving arrangement is achieved, whichis especially preferred with respect to the miniaturization ofcomponents.

The enclosure, however, can also be constructed as a cap. This has acontact surface for a bottom layer only in a peripheral edge region andrises therebetween above the contact level, so that sitting on flatbottom layers it can enclose underneath it a cavity. The cap is madefrom a rigid, electrically non-conductive material, for example,plastic. It is set on the carrier substrate and can be attached there,for example, by means of bonding or surface fusing. The MEMS chip isarranged in the cavity formed under the self-supporting cap.

It is also possible to arrange both the MEMS chip and also the chipcomponent under the enclosure formed as a cap or in some other way.Furthermore, it is also possible to provide an enclosure only for theMEMS chip and to arrange the chip component next to it on the carriersubstrate, but to provide both with a common shielding layer.

For various sensor functions of the MEMS chip, it is necessary that thisbe in direct contact with an outside atmosphere, especially when theMEMS chip is constructed as a pressure sensor or as a microphone. Forthis purpose, an opening through the shielding layer and the enclosureis provided above the MEMS chip, so that the MEMS chip is exposed to theoutside from this side. The subsequent production of the opening issimplified if the enclosure does not contact the MEMS chip directly atleast in a preferably central region, for example, it has a recess inthe bottom side or itself has a cap-like shape and is seated on the MEMSchip or the carrier substrate while enclosing a cavity. However, it isalso possible to provide the necessary opening in the carrier substrateunderneath the MEMS chip.

If the enclosure is made from an electrically insulating material, andin particular, from a close lying film or layer, then a metallizationstructure, which is connected in an electrically conductive way eitherto the MEMS chip or to the chip component or to two components arrangedone next to the other through contact holes formed in the firstenclosure layer, can be realized on a first enclosure layer. Above themetallization structure, a second enclosure layer is deposited as anelectrically insulating layer. The shielding layer is deposited abovethis second enclosure layer. With this metallization layer, connectionto the carrier substance can be realized from the MEMS chip and/or thechip component, and/or wiring can be realized between the two chips. Inthis case it is sufficient to attach components already electricallycontacted by means of the metallization structure onto the carriersubstrate by just mechanical means, for example, by adhesion bonding.

The MEMS chip can be attached, and in particular, bonded by anappropriate connection means onto the carrier substrate with its passiveside that is opposite the active side. If the MEMS chip has a viacontact running up to the active side with the active MEMS structures,then the connection means are made electrically conductive. It ispossible, for example, to use an electrically anisotropic conductiveadhesive, which guarantees electrical conductivity only transverse tothe adhesive layer. Such anisotropic conductive adhesive has theadvantage that it can be deposited over a large surface area, wherein aplurality of electrical connections can be simultaneously producedbetween corresponding contact surfaces on the MEMS chip and terminalsurfaces on the carrier substrate, without their being short-circuitedby the adhesive layer covering all of the contact surfaces.

In addition, the anisotropic conductive adhesive has the advantage thatthe separating joint between the carrier substrate and MEMS chip can becompletely closed off. This is especially advantageous if the productionof the enclosure and/or the metallic shielding layer can be realizedonly on a closed surface or if the bottom side of the MEMS chip has tobe protected for a corresponding process of applying the enclosure orshielding layer, or if a cavity is to be left under the enclosure. Thisis especially important if MEMS structures located on the bottom side ofthe MEMS chip are exposed, and an appropriate method for producing theenclosure or shielding layer includes the use of a liquid phase.

However, the MEMS chip can also be connected to the carrier substrate bymeans of bonding wires. This can be advantageously combined with a rigidenclosure, which protects the MEMS chip without negatively affecting thebonding wire connection.

The MEMS chip and chip component are preferably mounted on the carriersubstrate using flip-chip technology or one above the other, wherein thesurface with the electrical contacts faces toward the carrier substrateand electrical and mechanical connections are produced between contactand terminal surfaces corresponding to each other and opposite eachother in the mounted state, for example, by means of bump connections,solder connections, or electrically conductive adhesives.

The chip component can have an essentially smaller layer thickness thanthe MEMS chip. This allows the chip component to be arranged under theMEMS chip, that is, between the MEMS chip and carrier substrate. Thereit can be connected electrically and mechanically to the top side of thecarrier substrate. It is also possible to arrange the chip componentunder the MEMS chip and to form an electrical and mechanical connectionto the MEMS chip.

For a flip-chip arrangement of the MEMS chip by means of non-sealingconnections, an additional joint seal can be provided. This can be, forexample, an underfiller, which seals the joint peripherally from theoutside after placement of the MEMS chip.

It is also possible to provide on the top side of the carrier substrateor on the corresponding side of the MEMS chip a frame-like structurewhose top side represents an annular closed terminal surface for theMEMS chip or for the carrier substrate. The frame structure can be, forexample, a solder frame, which also allows it to produce a solderconnection between the carrier substrate and MEMS chip. However, theframe structure can also be made from a material that can be appliedstructured in some other way or structured at a later time, for example,one made from plastic, a structured plastic film, and in particular,from a structured resist.

However, it is also possible to form the frame structure integrated intothe material of the carrier substrate or the MEMS chip. Thecorresponding electrical connection or contact surfaces are then setback relative to the level of the top edge of the frame, so that whenthe corresponding part contacts the frame structure, there is stillspace between the MEMS chip and the carrier substrate for thecorresponding connection means, in particular, for the adhesive layer,solder connection, or bumps.

The MEMS chip and chip component can be arranged one next to the otheron the carrier substrate and can be covered with a common large surfacearea enclosure, in particular, a laminate film. Preferably, thearrangement is made so that the laminate film encloses the MEMS chip andthe one or more chip components separately against the top side of thecarrier substrate. The shielding layer is the applied over a largesurface area above the enclosure and preferably forms a seal with thetop side of the carrier substrate. Preferably, the MEMS chip is providedwith a cover arranged under the enclosure, which covers either thesensitive MEMS structures on the active side or spans an optionalupward-facing recess in the MEMS chip.

Even more advantageous is to use the chip component as the cover and touse at least one first laminate film as the enclosure which covers theMEMS chip provided with the chip component as the cover, and forms aseal all-around with the substrate. In this first enclosure layer,contact holes can be provided in which contact surfaces there exposedare connected to a metallization structure applied onto the firstenclosure layer. By means of this metallization structure, the chipcomponent can be connected electrically to terminal surfaces on the topside of the carrier substrate. The MEMS chip can be connectedelectrically and mechanically directly to the carrier substrate by meansof an electrically conductive connection. In this case it is possible tobond the chip component as a cover on the surface of the MEMS chip thatfaces away from the carrier substrate, so that the contacts of the chipcomponent point upward. However, it is also possible in addition toprovide a direct connection between the chip connection and MEMS chip.

Preferably, however, the electrical connection is realized on the layerof the carrier substrate, for example, by conductor tracks provided onits surface or by a metallization and wiring layer buried in theinterior of the carrier substrate or on the bottom side of the carriersubstrate.

The MEMS chip can be constructed as a microphone in which an opening isprovided in the enclosure and/or shielding layer or in which the MEMSchip is arranged above a sound opening in the carrier substrate. Inaddition, the MEMS package can have on the side opposite the soundopening or the perforation a sufficiently tightly closed back volumethat represents a reference pressure for the MEMS chip and allows themeasurement of a pressure difference relative to this referencepressure. This is necessary for applications as a pressure sensor ormicrophone.

The sound opening through which a MEMS chip constructed as a microphoneor pressure sensor is connected to the outside environment can be formedas an opening in the carrier substrate, or as a perforation in theenclosure or shielding layer.

The back volume or reference volume is then formed on the side of theMEMS chip opposite the sound opening. On the passive side the backvolume can be made available by a recess in the MEMS chip, and coveredor closed accordingly.

If the passive side of the MEMS chip faces the sound opening, then theback-side volume is made available from the enclosure or the carriersubstrate.

This can be realized in the form of a cover formed as a cap and sittingon the MEMS chip, or can be realized in the form of a cap sitting on thecarrier substrate.

If the active side is facing the carrier substrate with the soundopening, the back volume is provided, for example, in a recess in thecarrier substrate underneath the MEMS chip.

DESCRIPTION OF THE DRAWINGS

In the following, the MEMS package according to the invention and alsosuitable methods for its production will be explained in more detailwith reference to embodiments and the associated figures. The figuresare constructed purely schematically and not true to scale, so thatneither absolute nor relative dimensional information can be taken fromthe figures. Shown in detail are:

FIG. 1, a MEMS package, in which the MEMS chip and chip component arearranged under a cap and a metallic shielding layer and are contacted bymeans of bonding wires,

FIG. 2, an arrangement in which, in contrast to FIG. 1, the MEMS chip iscontacted electrically by means of a flip-chip arrangement,

FIG. 3, an arrangement in which, in comparison with FIG. 2, the cap isreplaced by a close-lying enclosure layer and the chip component has aglob-top encapsulation,

FIG. 4, a MEMS package in which, in contrast to FIG. 3, the chipcomponent also has a flip-chip arrangement and the MEMS chip is coveredwith a cover,

FIG. 5, an arrangement in which the MEMS chip applied in a flip-chiparrangement also has a joint seal and in which the enclosure layer iseliminated,

FIG. 6, an arrangement in which the chip component is attached to thecarrier substrate between the MEMS chip and the carrier substrate,

FIG. 7, an arrangement in which the chip component is arranged betweenthe MEMS chip and carrier substrate and is attached to the former,

FIG. 8, an arrangement in which the chip component lies on thethrough-contacted MEMS chip and is also covered with an enclosure havinga recess,

FIG. 9, an arrangement with the chip component lying on the MEMS chip,which are covered with a laminate film,

FIG. 10, an arrangement similar to FIG. 8, in which, however, aperforation is provided in the cover, enclosure, and shielding layer,

FIG. 11, an arrangement in which the chip component is arranged underthe MEMS chip on the carrier substrate in a recess of the MEMS chip, andin which a perforation is provided in the cover, enclosure, andshielding layer above the MEMS chip,

FIG. 12, an arrangement in which the MEMS chip and chip component arearranged one next to the other above a cavity in the carrier substrate,and wherein both cavities are connected to each other,

FIG. 13, an arrangement in which the chip component is arranged next tothe MEMS chip and is contacted electrically by means of a metallizationstructure,

FIG. 14, an arrangement in which the MEMS chip is covered with the chipcomponent and the chip component is connected in an electricallyconductive way to the carrier substrate by means of a metallizationstructure, and

FIG. 15, an arrangement in which a molded part with an additional recessis arranged between the MEMS chip and chip component.

DETAILED DESCRIPTION

FIG. 1 shows a simple embodiment of the MEMS package, in which the MEMSchip MC and chip component CB are mounted one next to the other on thetop side of the carrier substrate TS and are attached there, forexample, by means of adhesive. The electrical contacting of the twocomponents to the carrier substrate is realized with bonding wires BD.The enclosure AB is made from a cap sitting on the carrier substrate,which encloses underneath a cavity HR. The cap can be adhesively bonded,for example, on the carrier substrate TS and is made, for example, froma prefabricated plastic part. The shielding layer SL is applied on thecap and the surface of the carrier substrate with a thin-film method andis optionally reinforced with wet-chemical or galvanic methods. Forexample, a two-step process is suitable in which initially a metallicadhesive layer—for example, made from titanium, nickel, chromium,tungsten, or copper—is sputtered and then reinforced with copper ornickel with a galvanic or electroless method from solution.

Suitable layer thicknesses for fulfilling the shielding function thenlie in the range between 10 and 100 μm. Preferably, the carriersubstrate TS has a terminal surface connected to ground that seals theshielding layer and thus grounds the layer. The cavity HR under theenclosure AB formed as a cap is used as a back volume for the functionof the MEMS chip. The MEMS chip MC has, on the passive side facingtoward the carrier substrate, a recess AN in which the MEMS chip isthinned until the MEMS structures of the active side are exposed.Underneath the recess, an opening OE formed as a perforation is providedin the carrier substrate, so that the (passive) bottom side of the MEMSchip is connected in the region of the recess AN to an ambientatmosphere or an ambient pressure.

Not shown in the figure are external contacts arranged on the bottomside of the carrier substrate, by means of which the MEMS package can bemounted on a printed circuit board or another circuit environment.Naturally, the printed circuit board then also has a correspondingperforation, in order to guarantee, after assembly of the package, aconnection to the surrounding atmosphere. However, it is also possibleto provide external contacts on the top side of the carrier substrateand then to countersink the cap in a recess or opening of the printedcircuit board and then to mount the MEMS chip head first.

The MEMS chip MC is designed, for example, as a microphone, the chipcomponent CB, for example, as an amplifying component for themeasurement signals generated by the MEMS chip.

As a carrier substrate TS, typical printed circuit board substrates aresuitable in a multi-layer technology on a ceramic (HTCC—high temperaturecofired ceramics, LTCC—low temperature cofired ceramics) or organic(epoxy, phenol, polyimide, bismaleinimide triazine, cyanate, ester,cyanate ester, PTFE polytetrafluroethylene) base, optionally withinorganic filler materials (quartz or ceramic particles, glass fibers,glass film) or also with organic fiber reinforcement (e.g., aramide).Also suitable are high-temperature thermoplastics (e.g., PEIpolyetherimide, PAEK polyaryl ether ketone, PSU polysulfone, PPSpolyphenylene sulfide, PAI polyamidimide, PA polyamide, polyphthalamide,polybutylene terephthalate, or others) as the material for the carriersubstrate TS, especially those in MID processing (molded interconnectdevice). Passive or active components can be embedded in the carriersubstrate TS. In the case of a MEMS chip constructed as a microphone,these are in particular amplifiers or AD converters, and also devicesprotecting against EMI (electromagnetic interference) and ESD(electro-static discharge).

FIG. 2 shows another MEMS package, in which, in contrast to FIG. 1, theMEMS chip MC is attached in a flip-chip arrangement, e.g., by means ofbumps BU, onto the carrier substrate TS. For this purpose, the MEMS chipis inclined vertically relative to FIG. 1, so that now the active sideof the MEMS chip faces toward the surface of the carrier substrate. Theelectrical and mechanical connection can be realized by means of bumpsor electrically conductive adhesive. If the adhesive does notsufficiently seal the back volume under the enclosure AB formed as acap, so that the reference pressure provided there cannot be maintainedlong enough, then as shown in FIG. 2 a sealing frame DR (see figure), oralternatively an underfiller or some other joint seal, is provided sothat the edge of the MEMS chip is sealed peripherally against thecarrier substrate TS. The sealing frame can also be an adhesive appliedafter soldering of the MEMS chip MC. An anisotropic conductive adhesivecan replace the illustrated bumps BU and can simultaneously realize aseal. Compared with FIG. 1, the back volume here is further enlarged.

FIG. 3 shows an arrangement in which the MEMS chip MC and chip componentCB are placed as in FIG. 2. Unlike there, here the chip component CB iscovered, but with a directly applied protective encapsulation, forexample, a glob-top mass LG. An enclosure layer, for example, alaminated laminate film, is applied as another enclosure AB both abovethe MEMS chip MC and also above the chip component CB provided with theprotective enclosure LG. This fits tightly against the MEMS chip MC andcan, as shown, span the recess AN on the (passive) bottom side of theMEMS chip MC. The shielding layer SL is in turn applied as a metalliclayer on the surface of the enclosure layer, and forms an overall sealwith the carrier substrate TS.

Due to the reduced back volume relative to FIGS. 1 and 2, if a backvolume is actually required for the MEMS chip MC then this is selectedto be sufficiently large. For this purpose, the recess AN is eitherenlarged or the thickness of the MEMS chip is increased until asufficiently large back volume is obtained. For suitable processingcontrol, especially if the enclosure layer tightly seals the back volumeon the MEMS chip, then the sealing frame DR can be eliminated here.

FIG. 4 shows a construction for a MEMS package in which the chipcomponent CB is also placed in a flip-chip arrangement next to the MEMSchip MC on the carrier substrate TS. Because the electrical contacts ofthe chip component CB are protected in the intermediate space betweenthe chip component and carrier substrate, here no additional enclosureof the chip component is required as in FIG. 3. The enclosure AB formedas an enclosure layer can lie directly on the reverse side of the chipcomponent.

In another construction, a cover DL is placed above the MEMS chip MC.This simplifies the application of the enclosure layer, especially thelamination of the laminate film, in that it covers the recess on the topside of the MEMS chip MC and in this way encloses the back volume. Forthe cover DL a glass or plastic film, or alternatively, an appropriatelythinned semiconductor layer can be used. A sufficient thickness isobtained at ca. 100 μm. Preferably, the MEMS chip is already provided atthe wafer level with the cover, in which a correspondingly large surfacearea cover layer or a corresponding cover wafer is connected to thewafer in which the MEMS chip MC is advantageously produced. Theconnection of the MEMS wafer to the cover wafer can be effected, forexample, by means of wafer bonding. Adhesive is also possible.

FIG. 5 shows an arrangement in which the enclosure layer is eliminated.The MEMS chip is covered only with a cover DL, which seals the backvolume in the recess AN. If the MEMS chip MC is not attached with anelectrically anisotropic conductive adhesive and thus already sealed,then the joint between the MEMS chip and carrier substrate TS is alsosealed with a joint seal FD, for example, a sealing frame or anunderfiller. This arrangement now allows a shielding layer SL to beapplied directly onto the cover, the side surfaces of the MEMS chip andthe surface of the carrier substrate, without having to take intoaccount a negative effect on the MEMS function.

For depositing the shielding layer for the arrangement according to FIG.5, processes of deposition from metal solutions can also be used,because a corresponding seal is bestowed on the MEMS chip. Here, thesound opening OE in the carrier substrate needs only to be temporarilyclosed, or one must proceed such that the sound opening is not exposedto the liquid. The chip component CB is preferably adhesively bonded toan anisotropic conductive adhesive, so that also here no additional sealis necessary. Not shown but also possible is to seal the chip componentwith a joint seal against the carrier substrate, in order to protect thecontacts before the process of applying the shielding layer SL.

FIG. 6 shows a space-saving construction of a MEMS package in which thechip component CB is attached directly onto the carrier substrate TS notnext to, but rather under the MEMS chip MC. In this way, the chipcomponent CB can cover the opening OE in the carrier substrate as shown,so that the MEMS chip MC can nevertheless be in direct contact with theambient atmosphere outside of the package and can receive acorresponding pressure. This construction is optimum with respect to theminimum required carrier substrate surface.

As another feature that can be combined independently with otherconstructions, here the MEMS chip MC is provided with a cover DL whichhas a cover recess above the recess AN of the MEMS chip itself, or isconstructed as a cap sitting on the MEMS chip. The cover recessincreases the back-side volume. The enclosure AB covers the MEMS chip orthe cover and together with a shielding layer SL deposited abovesimultaneously guarantees sealing of the MEMS chip against the carriersubstrate. In this case it is also possible to eliminate the enclosurelayer and to optionally provide a joint seal on the MEMS chip bottomside.

With a slight modification relative to FIG. 6, FIG. 7 shows a chipcomponent CB similarly arranged under the MEMS chip MC, but connected toits bottom side. Here the chip component is placed so that the bottomside of the MEMS chip contacts the outside atmosphere. The remainingseal can be realized as shown in one of FIGS. 4 to 6, or as in FIG. 7.

For simplifying the method, the chip component CB can be already put inplace on the wafer level on a MEMS chip wafer in which the MEMS chip isformed, before the individual MEMS chips are separated. Here it ispossible to apply the chip component CB on an auxiliary carrier in asuitable pattern, so that the application of the chip component can beperformed in parallel and simultaneously by means of the auxiliarycarrier in the same way for all of the MEMS chips on the wafer.

FIG. 8 shows another carrier substrate surface-area-saving constructionof a MEMS package, in which the chip component CB is placed on the(passive) top side of the MEMS chip MC, preferably in a flip-chiparrangement, which allows a simultaneous electrical connection of thechip component to the MEMS chip. For this purpose, the MEMS chip isprovided, as shown, with a via contact DK which produces an electricalconnection to the active side of the MEMS chip. The MEMS structures onthe active side are in turn connected by means of correspondingconductive connections to terminal surfaces (not shown in the figure).An arbitrary number of via contacts and an optionally even larger numberof contact surfaces are provided on the bottom side of the MEMS chip,which correspond to the required connections for the MEMS chip and thechip component CB. However, it is also possible to combine or divideconnections, wherein the number of via contacts and connectionsincreases or decreases accordingly.

If the chip component CB is not sufficiently mechanically stable, it canalso be covered with a cap which sits on the MEMS chip and acts as acover DL. The cap form can also be realized by a cover recess ofcorresponding size on the bottom side of the cover. The enclosure layerAS and shielding layer SL expand the arrangement. If necessary, theenclosure layer can also be eliminated.

FIG. 9 shows another construction for a MEMS package in which the chipcomponent CB represents the cover for the MEMS chip MC, which issufficiently stable so that an enclosure layer can be deposited orgenerated directly above as an enclosure AB without stability problems,and above this a shielding layer SL can be deposited or generated. Thechip component is here preferably already connected at the wafer levelto the MEMS wafer in which the individual MEMS chips are structured. Forthis purpose, the chip component is preferably coextensive with the MEMSchip, so that the two wafers can be connected to each other directlysince they have the same pattern in the separation. However, it can benecessary here to realize electrical connections on the top side of thechip component by means of via contacts through the chip component (asshown in FIG. 9). Placement of the chip component in a flip-chip processon the (active) top side of the MEMS chip (not shown in FIG. 9) can forma direct electrical connection to corresponding connections of the MEMSchip, so that the via contacts through the chip component are then notnecessary. The connection can be realized by means of solder oradvantageously with anisotropic conductive adhesive.

FIG. 10 shows an arrangement in which the MEMS chip MC is connected tothe carrier substrate TS via its base chip or its passive side, incomparison with the previous arrangements shown in FIGS. 2 to 9. Thismeans that the back-side volume guaranteed by the recess AN in the basechip is now sealed off by the carrier substrate TS. The contact of theMEMS chip MC with the surrounding atmosphere must then be realized bymeans of a perforation DB in the cover DL, enclosure AB, and shieldinglayer SL. If the enclosure AB has sufficient stability, the cover DL canbe eliminated and the cavity can be guaranteed, e.g., via a sacrificiallayer on the MEMS chip which can be removed again after application ofthe enclosure AB and shielding layer and also after the opening of theperforation DB. The perforation DB can be generated in both cases aftercompletion of the enclosure AB and after application of the enclosurelayer and the shielding layer SL, for example, by drilling, inparticular, by laser drilling. Larger or several smaller perforationscan be provided.

FIG. 11 shows an arrangement which similarly encloses the back-sidevolume between the MEMS chip and carrier substrate in the region of therecess AN. The volume is sufficient so that the chip component CB hasroom in the volume and can be connected to the carrier substrate TSunder the MEMS chip in the region of the recess, for example, in aflip-chip arrangement by means of electrically conductive adhesive,bumps, or other bonding connection. Here, a connection of the top sideof the MEMS chip MC to the surrounding atmosphere must be guaranteed bymeans of a perforation DB.

Because the back-side volume is limited to the chip size of the MEMSchip MC and is possibly too small according to the arrangement accordingto FIGS. 10 and 11, it can be enlarged by additional cavities VK in thecarrier substrate TS. FIG. 12 also shows a construction in which anothercavity is additionally provided under the chip component CB, this beingconnected to the cavity VK under the MEMS chip MC. The back-side volumeis further enlarged without increasing the structural height or thesurface area of the MEMS package.

FIG. 13 shows a construction in which a metallization structure MS isarranged above a first enclosure layer AS1 and a second enclosure layerAS2 is arranged above this structure. The metallization structureconnects electrically to contact surfaces of the chip component CB andterminal surfaces of the carrier substrate TS by means of contact holesKB in the first enclosure layer AS1 and thus represents an electricalconnection structure. Therefore the chip component CB can be adhesivelybonded onto the carrier substrate with the reverse side.

In FIG. 14, similar to FIG. 9, the MEMS chip MC is covered with thebonded chip component CB as a cover. The electrical connection of thechip component to the terminal surfaces of the carrier substrate TS isalso realized here by means of a metallization structure MS, as shown inFIG. 13, which is connected to the contact surfaces of the MEMS chip MCby means of contact holes KB. The MEMS chip makes direct contact withthe carrier substrate or its contact surfaces.

In none of the described embodiments is the back volume of the MEMS chiplimited to the shown form (funnel-like opening), which is produced,e.g., by a defined etching method in single crystals, such as, e.g.,silicon. Instead, other forms of the recess (vertical walls) can be moreadvantageous for reducing the MEMS chip. On the other hand, however, thechip-specific back-side volume formed by a recess could become toosmall, which would degrade the sensitivity of the microphone. One aid isalready shown in FIG. 6, in which the enclosure AB has an additionalrecess.

If the chip component CB is to be used as a chip enclosure for the MEMSchip MC and in this way an additional back-side volume is to be created,the following solution is shown in FIG. 15. It has proven especiallyadvantageous when the MEMS chip and chip component are to be alreadyjoined at the wafer level, even though the chip component is smaller. Inthis case, in a preliminary step, the (smaller) chip component is setwith its connection side on an auxiliary carrier (e.g., an adhesivefilm), that is, at the spacing of the (larger) MEMS chip. In order toachieve a matched thermal expansion coefficient, this arrangement isthen coated with a filled polymer filler FM, e.g., in a casting,pressing, or laminating process. In this way, a new wafer is obtained inwhich the chip components are now arranged fitting the counterpart. Inthis processing step an additional cavity HR can be pressed into themolded material FM in a simple way. For placement and bonding of the newwafer, the additional cavity is arranged above the MEMS chip MC andoptionally forms, together with its recess AN, the back-side volume.

In a modified construction, an intermediate position with an additionalcavity can also be formed by a separate molded part.

In addition, other combinations of the described details are alsopossible in modification of the shown constructions.

All of the embodiments are also especially suitable for arrays made fromtwo or more MEMS chips formed as microphones. In this way directionalcharacteristics can be set, for example, for reducing ambient noise. Theback-side volumes are here allocated individually to each MEMS chip. Incontrast, the electronic circuitry can combine several of these volumes.

The shielding layer SL on the top side of the carrier substrate on whichthe MEMS chip and possibly other components are located is of essentialsignificance for shielding the sensitive internal signal processingrelative to external interference fields. This is especially relevantfor use in mobile telephony, where the component is often arranged onlya few centimeters from the antenna. The processing sequence discussedabove, lamination-sputtering-electroplating, is only one possibility forproducing this coating with good conductivity. In a few embodiments,e.g., the lamination process can be eliminated (cf. FIG. 5). It is alsopossible to produce a corresponding layer through dipping, casting, orspraying instead of lamination. For the metallization of plasticsurfaces, a series of PVD, CVD, wet-chemical, and galvanic methods (orcombinations of these) is known. For a structured metallizationstructure MS (see FIGS. 13, 14, 15) for the purpose of circuitry, theirphotolithographic structuring or a selective metallization is provided,e.g., laser-activated deposition or direct writing of the metallizationstructure with a jet printing method.

All of the packaging variants described above with the example of a MEMSmicrophone or shown schematically in the figures are also suitable, inprinciple, for any other electronic components, especially for theenclosure of other MEMS chips including amplification, matching, orevaluation electronics. Typical examples are mechanical resonators andfilters, pyrosensors, spectrometers, image converters in the visible orinfrared spectral range, pressure sensors, gas sensors, turbiditysensors, loudspeakers, motion detectors, acceleration or gyro sensors,RFID chips, switches, tunable high-frequency components (“varactors”),fuel cells, thermoelectric generators, and many others.

Naturally, the sound opening can be eliminated. Then, with a suitablecarrier substrate material, if necessary a hermetic and non-diffusionconstruction is possible or can be replaced by a window for other wavesor radiation, or by a media inlet. The back side volume is then alsoobsolete in many cases.

1. A micro electro-mechanical systems (MEMS) package, comprising: acarrier substrate having a top side, a MEMS chip mounted on the top sideof the carrier substrate, the MEMS chip having an active side facing thecarrier substrate and a passive side facing away from the carriersubstrate, the passive side including a recess formed in the MEMS chip;a cover in contact with a portion of the passive side of the MEMS chipand covering the recess in the passive side of the MEMS chip to enclosea back volume of the MEMS chip; at least one chip component on the topside of the carrier substrate beside the MEMS chip, and a thin metallicshielding layer covering the MEMS chip and the at least one chipcomponent and forming a seal with the top side of the carrier substrate,wherein the MEMS chip and the at least one chip component areelectrically connected to each other or with external contacts on thecarrier substrate.
 2. The MEMS package of claim 1, further comprising anenclosure between the metallic shielding layer and the MEMS chip.
 3. TheMEMS package of claim 2, wherein the enclosure comprises a laminate filmapplied over a large surface area above the MEMS chip and the at leastone chip component, the laminate film forming a seal with the carriersubstrate.
 4. The MEMS package of claim 1, wherein the cover includes arecess facing the MEMS chip and encloses a cavity above the MEMS chip.5. The MEMS package of claim 1, wherein the at least one chip componentis on the MEMS chip under the shielding layer.
 6. The MEMS package ofclaim 2, wherein the enclosure includes a perforation above the MEMSchip.
 7. The MEMS package of claim 2, wherein the enclosure comprises arigid cap on the carrier substrate and forms with the carrier substratea cavity, wherein the MEMS chip is in the cavity and wherein theshielding layer is directly on the rigid cap and on the carriersubstrate in an edge region around the rigid cap.
 8. The MEMS package ofclaim 1, wherein the MEMS chip includes an active side comprising MEMSstructures, and a central recess in a passive side opposite the activeside, the passive side facing toward the carrier substrate, wherein alayer thickness of the MEMS chip is reduced in the central recess or theMEMS structures are exposed in the recess.
 9. The MEMS package of claim8, wherein the MEMS chip includes electrical via contacts, and the MEMSstructures are electrically connected to terminal surfaces on thecarrier substrate by the electrical via contacts.
 10. The MEMS packageof claim 8, wherein: the MEMS chip is bonded to the carrier substrate onthe passive side, and the active side includes electrical contactsurfaces electrically connected by bonding wires to terminal surfaces onthe carrier substrate.
 11. The MEMS package of claim 8, wherein: theactive side of the MEMS chip faces toward the carrier substrate, andcorresponding electrical contact surfaces on the active side of the MEMSstructures and terminal surfaces on the carrier substrate are facingeach other and are electrically and mechanically connected.
 12. The MEMSpackage of claim 1, wherein the chip component is under the MEMS chip onthe top side of the carrier substrate, and is electrically connected toterminal surfaces on the carrier substrate.
 13. The MEMS package ofclaim 1, wherein the chip component is under the MEMS chip and iselectrically and mechanically connected to the MEMS chip.
 14. The MEMSpackage of claim 11, further comprising a joint between the MEMS chipand the carrier substrate sealed by a joint seal.
 15. The MEMS packageof claim 1, wherein the shielding layer is on the MEMS chip tightlycontacts the cover, side surfaces of the MEMS chip and the top side ofthe carrier substrate.
 16. The MEMS package of claim 1, wherein: theMEMS chip and the at least one chip component are one next to the otherand are electrically connected to terminal surfaces on the carriersubstrate, the enclosure seals the MEMS chip and the chip component tothe carrier substrate separately, and the shielding layer covers theMEMS chip and the chip component.
 17. The MEMS package of claim 16,wherein: the active side of the MEMS chip is electrically andmechanically connected to the carrier substrate by one or more of bumpsand electrically conductive adhesive, the cover is on the passive sideof the MEMS chip facing away from the top side of the carrier substrate,the MEMS chip, the cover, and the at least one chip component arecovered with the laminate film, and the shielding layer is on an outwardsurface of the laminate film.
 18. The MEMS package of claim 1, wherein:the MEMS chip comprises a microphone, a perforation is provided in oneor more of the enclosure and the shielding layer, or the MEMS chip isabove a sound opening in the carrier substrate, and the MEMS packagefurther comprises a closed back volume on a side of the MEMS chipopposite the sound opening or the perforation.
 19. The MEMS package ofclaim 18, wherein: the MEMS chip and the at least one chip component aremounted one next to the other on the carrier substrate, the cavity isformed in the carrier substrate under the at least one chip component,and the cavity is connected to the closed back volume under the MEMSchip.
 20. The MEMS package of claim 17, wherein the electricallyconductive adhesive has an anisotropic conductivity perpendicular to anadhesive layer.
 21. The MEMS package of claim 1, wherein the carriersubstrate comprises a diffusion-resistant material and the shieldinglayer binds tightly to the diffusion-resistant materialcircumferentially.